I have the factory parts books and they show that the Midland power brake booster was an option on the F100 for 1956. There is also some information in the 1956 Ford Truck Shop Manual about repairs. Interestingly, there is no part number listed for the bracket, flexible brake hose or any other components of the installation.
It appears the ILL page was left out of the FINAL EDITION 1964 for whatever reason. You would need to find an earlier printings).
Are you wanting OEM or possibly thinking about an upgrade?